Components which are used at high temperatures often form an oxide layer, during which process “metallic” atoms diffuse out of the component to the component/metal oxide interface and this metal element is depleted in the component in the region below the oxide layer.
Gas turbine components which are exposed to hot gases are often protected by thermal barrier coatings on MCrAlX bonding layers. The bonding of the thermal barrier coating to the MCrAlX layer is substantially produced by an aluminum oxide layer between the MCrAlX layer and the thermal barrier coating. However, the aluminum oxide layer (thermally grown oxide—TGO) grows during operation, until ultimately the bonding fails.
The MCrAlX layers are often provided with a platinum plating, which as a diffusion barrier is supposed to slow down the growth of the TGO. One problem is that this process is expensive, since pure platinum is used and an additional coating process increases costs. A further problem is that during operation the platinum diffuses into the component substrate. However, during refurbishment of the component this leads to a change in the known refurbishment processes, since the platinum increases the attack of acid on the substrate.